   [day rowNum]
   (nth (timetable-get-day day) rowNum))
 
-; First argument is a day in `Timetable - the return value of
+; First argument is a day in `TIMETABLE` - the return value of
 ; `timetable-get-day` function
 (defmethod timetable-get-day-row false
   [ttDay rowNum]

    (attr thElem "rowspan" nrRows)))

(defn- timetable-add-lesson!
  "Adds a lesson to the `Timetable` global, effectively 'marking' the
   time interval for that lesson as being occupied."
  [day rowNum ttLessonInfo $lessonDiv]
  (set! Timetable
        (update-in Timetable
                   [day rowNum]
                   (fn [ttRow]
                     (assoc ttRow ttLessonInfo $lessonDiv)))))

;
; TimetableLessonInfo (abbrev: ttLessonInfo)
; ------------------------------------------
; Describes a lesson in the `TIMETABLE` global; this is the key used for each
; row in a day of the `TIMETABLE`.
;
; Each instance of `TimetableLessonInfo` is a map in the following format:
;
